1. Field of the Invention
The present invention relates to a method for storing and transferring a raw material for a dissolving or sintered metal.
2. Description of the Related Art
A raw material of a sintered metal, and a raw material for growing a gallium arsenide crystal, a silicon single crystal or a polycrystalline silicon for a semiconductor have been stored in a plastic film for growing. When used, the plastic film is opened and the raw material is put into a mold in process.
Especially during a crystal production process, a quartz crucible has been stuffed with the raw material at room temperature, and has been stored or put in a furnace.
For example, JP 2009-127085A discloses a surface treatment method for obtaining a dry material of metal fine particles storable for a long time, and a method for storing the dry material. The method for obtaining the dry material of the metal fine particles re-dispersable in water comprises adding a flocculant to water in which the metal fine particles adsorbed with a surfactant and a lipid are dispersed, making the metal fine particles aggregated and settled out, and drying in a vacuum the aggregation of the settled metal fine particles.
However, for a raw crystal for growing a highly purified semiconductor crystal, it is necessary to highly remove impurities from the raw crystal. When the raw crystal is placed in the air, a slight amount of substances such as air or water is adsorbed on the surface. Therefore, most of the adsorbed substances should be removed at the initial stage because the substances affect improvements of quality of products and durability of parts in a furnace.
As described above, the related art, for example, JP 2009-127085A discloses a method for obtaining a dry material re-dispersable in water. However, in order to grow a sintered metal material or a semiconductor crystal to obtain a polycrystal, the raw material requires high purity. In addition, a slight amount of water adsorbed on a surface of the raw material may cause a deterioration of parts in a furnace in the following step of growing a crystal. Moreover, carbon reacted with water may be incorporated into the grown crystal.
Patent Literature 1: JP 2009-127085A